Nikon 105mm f/2.8 Micro [AI-S]
Nikon's CRC (Close Range Correction) with range-correcting floating elements design gives Nikon's macro lenses a very even image quality over their entire focusing range, from the macro region to infinity. This also the case with this lens. It is good wide open at f/2.8, but peak sharpness occurs at f/5.6 and f/8. Sharpness deteriorates beyond f/16 due to diffraction. Despite being a macro lens, best performance is actually outside the macro region. Many therefore use this a a portrait lens.
The lens only let you focus at half life size. To go beyond 1:2, it's necessary to add the PN-11 (52.5 mm) extension ring, bringing the minimum focus distance from 47 cm to 41 cm. However, CRC does not take an extension ring into account. With the PN-11 fitted, Nikon recommends that the lens is stopped down more to f/5.6 to retain a flat-field. The lens flares easily and the use of lens shade HS-4 or HS-14 is recommended. Due to the CRC design, the focal length is 88 mm at 1:2.
Nikon has erroneously reported the formula of this lens as a 9 groups with 10 elements. This error has persisted in most descriptions of this lens you'll find. It is really 8 groups with 9 elements (see diagram below).
The lens is fitted with a chrome screw that is supposed to lock focus on a preset distance to prevent creep. However, I have yet to see an sample where this tightening this screw has any effect. On the other hand, creep is not a problem with this lens.
On the lens barrel, there are several markings. At the bottom, there is the aperture setting ring. Above that, there is a typical distance scale with meters (white) and feet (yellow). Then, in bright orange, there two rows of numbers showing reproduction ratio without and with PN-11 extension tubes. At the top, there a a mysterious row of numbers with aperture-ranges. Lines connect these numbers to the PN-11 reproduction ratios. The range 2.8~32 is connected to 1:1, 4~32 is connected to 1:1.3, 5.6~32 is connected to 1:1.6, 11~32 is connected to 1:2. The most obvious interpretation is that these are suggested aperture ranges to use with the PN-11 extension tube. This interpretation conflicts with other advise about how to use this lens. Apertures smaller than f/16 should be avoided because of diffraction, and at 1:1, the lens should be stopped down to f/5.6 to retain a flat field. If anyone familiar with the lens or have the manual for the lens knows what the “official” word on these aperture-range markings, please let me know.
Rating: Ed: -, User: - (normalized, 0=useless, 50=average, 100=excellent).
Mount: Nikon F.
Aperture range: f/2.8 to f/32.
Close focus distance (CFD): 47 cm / 1.54 ft (from sensor plane).
CFD magnification: 1:2 / 0.5X.
Filter diameter: 52 mm.
L x D, W: 84 x 67 mm, 515 g.
IR: Poor IR performance.
Approximate street price: USD 770 (new, w/o tax).
Production: 1983-2008, replaced by: Nikon 105mm f/2.8 G ED-IF AF-S VR Micro.
Nikon is a multinational corporation headquartered in Tokyo, Japan specializing in optics and imaging. Its products include cameras, lenses, flash units, scanners, binoculars, microscopes, measurement instruments, and steppers (used in semiconductor fabrication). The company was founded in 1917 as Nippon Kōgaku Kōgyō Kabushikigaisha (Japan Optical Industries Corporation), and renamed Nikon Corporation, after its cameras, in 1988. Nikon Corporation is one of the companies of the Mitsubishi Group.